title: An insertion of oleate desaturase homologous sequence silences via siRNA the functional gene leading to high oleic acid content in sunflower seed oil.
abstract: Classical sunflower varieties display a high linoleic acid content in their seeds [low oleic (LO) varieties] whereas genotypes carrying the Pervenets mutation display an increased oleic acid content of above 83% [high oleic (HO) varieties]. Despite the advantage in health terms of oleic acid, the nature of the mutation was still unknown. Previous work reported that HO genotypes carried a specific oleate desaturase (OD) allele. This enzyme catalyses the desaturation of oleic acid into linoleic acid. The present work demonstrates that this allele is organised in two parts: the first section present in both HO and LO genotypes carries a normal OD gene, the second section is specific to HO genotypes and carries OD duplications. The study of mRNA accumulation in LO and HO seeds revealed that the mutation is dominant and induces an OD mRNA down-regulation. Furthermore, OD small interfering RNA, characteristic of gene silencing, accumulated specifically in HO seeds. Considered together, these observations show that the mutation is associated with OD duplications leading to gene silencing of the OD gene and consequently, to oleic acid accumulation. This finding allowed the development of molecular markers characterising the mutation that can be used in breeding programmes to facilitate the selection of HO genotypes.
authors.affiliation: Monsanto SAS, Croix de Pardies, BP 21, 40305, Peyrehorade Cedex, France.
authors.forename: Séverine
authors.initials: S
authors.lastname: Lacombe
authors.forename: Irénée
authors.initials: I
authors.lastname: Souyris
authors.forename: André J
authors.initials: AJ
authors.lastname: Bervillé
mesh_terms: D000483:Alleles; D001483:Base Sequence; D001947:Breeding; D017931:DNA Primers / Q000235:genetics; D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism*; D020440:Gene Duplication; D020868:Gene Silencing; D005799:Genes, Dominant; D017343:Genes, Plant; D005819:Genetic Markers; D005838:Genotype; D006368:Helianthus / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D019301:Oleic Acid / Q000032:analysis / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics* / Q000378:metabolism*; D010938:Plant Oils / Q000737:chemistry / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D000074242:Sunflower Oil
chemical_list: D017931:DNA Primers; D005819:Genetic Markers; D010938:Plant Oils; D012333:RNA, Messenger; D018749:RNA, Plant; D034741:RNA, Small Interfering; D000074242:Sunflower Oil; D019301:Oleic Acid; D044943:Fatty Acid Desaturases; C021904:Phosphatidylcholine desaturase; D044925:Oxidoreductases Acting on CH-CH Group Donors